Thanks to Graniterich for providing some dimensions of the Harbor Freight 1720LB Super Duty 4x8 trailer!
I have an idea for a standy on an unmodified HF trailer. The idea I have would overhang the front and back of the cargo area of the trailer by one foot and each side by about 6". The height from the frame up would be about 6' 6". The rear would have a bed while the front would have a counter and a small area for a potty.
Below is a draft of how it might look. I would sure appreciate any thoughts anybody might have for this draft. Thanks!